1. Field of the Invention
This invention relates to a weft threading system for a fluid jet loom, and more particularly to improvements in an arrangement for automatically threading a weft yarn from a weft storage unit to a downstream side device under influence of a fluid jet.
2. Description of the Prior Art
An arrangement for automatically threading a weft yarn from a weft storage unit to a weft inserting nozzle has been proposed to be effected hen mispick occurs in a fluid jet loom, as disclosed in Japanese Provisional Publication No. 60-2479. During weaving operation of the loom provided with such an arrangement, the weft yarn drawn out from a weft supply member or bobbin is passed from the drum of a weft storage unit through a guide nozzle under an inoperative condition into a weft inserting nozzle. When mispick occurs under breakage of the weft yarn, weft threading operation is carried out as follows:
(1) When the weft yarn is broken or cut between the guide nozzle and the weft inserting nozzle, a suction pipe provided with a cutter is first moved from its withdrawal position to its operative position to suck and cut the weft yarn projected from the guide nozzle toward the side of the weft inserting nozzle. Subsequently air jet ejection is o made from the guide nozzle and from the weft inserting nozzle thereby to cause the weft yarn to fly toward the weft inserting nozzle under the influence of air jet ejected from the guide nozzle. The thus flying weft yarn is threaded into the weft inserting nozzle under suction generated at the inlet of the weft inserting nozzle.
(2) When the weft yarn is broken or cut between the weft storage unit and the guide nozzle, a guiding suction pipe provided with a fluid ejection nozzle is moved from its withdrawal position to its operative position on the side of the drum of the weft storage unit. Subsequently, air ejection is made from the fluid ejection nozzle of the guiding suction pipe, from the guide nozzle and from the weft inserting nozzle. Accordingly, the weft yarn wound on the drum of the weft storage unit is sucked into the guiding suction pipe and guide to the inlet of the guide nozzle. The thus guided weft yarn is threaded into the guide nozzle under suction generated at the inlet of the guide nozzle, and thereafter threaded into the weft inserting nozzle.
However, with the above-discussed arrangement, the suction pipe, the guide nozzle and the guiding suction pipe are adapted to move between their withdrawal position to operative position and therefore the construction of the arrangement and a mechanism for operating them unavoidably become complicated and large-sized while complicating devices around the weft storage unit and the weft inserting nozzle. This complicates control operations of the loom while making difficult maintenance and repair of the loom.